Json 合并二维数组的Jolt表达式

发布于03月08日

所以我有地理坐标，我想创建多边形字符串，我可以将其作为几何类型插入到Postgres中.我正在使用apache Nifi.

输入:

预期输出:

POLYGON((13 52, 13 55, 14 15))

我try 了下面的颠簸，但没有成功:

[
  {
    "operation": "shift",
    "spec": {
      "*": {
        "*": "[&1].[&0]"
      }
    }
  },
  {
    "operation": "shift",
    "spec": {
      "*": {
        "*": "&"
      }
    }
  },
  {
    "operation": "modify-overwrite-beta",
    "spec": {
      "*": {
        "*": "=join(' ',@(1,&))"
      }
    }
  },
  {
    "operation": "modify-overwrite-beta",
    "spec": {
      "*": "=concat('POLYGON((',@(1,2),'))')"
    }
  }
]

推荐答案

您可以将当前版本转换为以下格式:

[
  { // form independent arrays with keys of indexes taken from the outermost array
    "operation": "shift",
    "spec": {
      "*": {
        "*": "&1"
      }
    }
  },
  { // stringify those arrays
    "operation": "modify-overwrite-beta",
    "spec": {
      "*": "=join(' ',@(1,&))"
    }
  },
  { // generate an array namely "Coord"
    "operation": "shift",
    "spec": {
      "*": {
        "@": "Coord"
      }
    }
  },
  {
    "operation": "modify-overwrite-beta",
    "spec": {
      "Coord": "=join(' ,',@(1,&))",
      "*": "=concat('POLYGON((',@(1,&),'))')"
    }
  }
]

现场https://jolt-demo.appspot.com/上的demo个是: